drahkar

This plugin allows WordPress to authenticate users against an Active Directory. 
Developed to be compatible with current Active Directory releases as well as allow 
for Enterprise level Forest Deployments by allowing you to enter custom BaseDNs.
If you have bugs, suggestions, desires or requirements that you would like to see added 
to this, please come to the plugin page and submit them there so I can keep track 
of them as they are found and resolved.
This plugin is redeveloped off of <a href="https://wordpress.org/extend/plugins/simple-ldap-authentication/" rel="ugc">Simple LDAP 
Authentication</a>.
<h4>How to use</h4>
You can use this plugin in a few different ways.
<ol>
<li>
You can create WordPress accounts which match the names of your Active Directory accounts, and create these users from within the WordPress Users panel. Only the users you create in WordPress will be able to log in.
</li>
<li>
You can tick a checkbox so that anyone who can authenticate via Active Directory can log on. A WordPress account will be automatically created for the user if one does not already exist, with the default user role.
</li>
<li>
You can list the names of Active Directory groups who you want to allow to log on to WordPress. For each group in Active Directory, you can specify a corresponding WordPress user role.
</li>
</ol>
You can also combine the above however you like.

Simple AD Authentication

Authenticates users through Active Directory.

onelogin

This SAML plugin eliminates passwords and allows you to authenticate WordPress users (typically editors) against your existing Active Directory or LDAP server as well increase security using YubiKeys or VeriSign VIP Access via OneLogin. OneLogin is pre-integrated with thousands of apps and handles all of your SSO needs in the cloud and behind the firewall.
<ul>
<li>Eliminate passwords in WordPress</li>
<li>Allow users to sign into WordPress with their Active Directory or LDAP credentials</li>
<li>Give users one-click access from your intranet</li>
<li>Increase security using browser PKI certificates or two-factor authentication from Yubico or VeriSign</li>
<li>Easily prevent access from former employees and contractors</li>
</ul>
If you used this plugin before 2.2.0 with just-in-time provision active, Read: https://wpvulndb.com/vulnerabilities/8508 
To mitigate that bug, place the script at the root of wordpress and execute it (later remove it) https://gist.github.com/pitbulk/a8223c90a3534e9a7d5e0a93009a094f

OneLogin SAML SSO

This plugin provides single sign-on via SAML and gives users one-click access to their WordPress accounts from identity providers like OneLogin.

Simple AD Authentication vs OneLogin SAML SSO